didset Questions

4

Solved

I'm testing this and it appears that if you change the value within didSet, you do not get another call to didSet. var x: Int = 0 { didSet { if x == 9 { x = 10 } } } Can I rely on this? Is i...
Loseff asked 2/10, 2016 at 16:24

5

Solved

What is the difference between willSet - didSet, and get - set, when working with this inside a property? From my point of view, both of them can set a value for a property. When, and why, should ...
Spiro asked 20/8, 2014 at 7:10

9

Solved

Question Apple's docs specify that: willSet and didSet observers are not called when a property is first initialized. They are only called when the property’s value is set outside of an initi...
Cantina asked 10/8, 2014 at 16:38

3

Solved

I have a SwiftUI (Beta 5) view with an attached ViewModel. I want to navigate to it via a navigationLink and pass in a simple parameter (called FSAC in this case) I navigate using NavigationLink(&q...
Wariness asked 13/8, 2019 at 20:39

5

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If I attempt to run the following code: photographer = photographer I get the error: Assigning a property to itself. I want to assign the property to itself to force the photographer did...
Poppas asked 10/8, 2015 at 22:31

1

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I have a general problem using toggles with SwiftUI. Whenever I use them I get this console error: invalid mode 'kCFRunLoopCommonModes' provided to CFRunLoopRunSpecific - break on _CFRunLoopErr...
Teen asked 10/2, 2020 at 18:1

0

I would like to observe changes to @Binding property in subview. But there didSet/willSet is not called (it is called only if I change this variable from current view, but if change is from outside...
Niue asked 10/12, 2019 at 15:46

3

Solved

When I override the function noise, the function gets replaced by the new one. But when I override a property with an observer, the old and new value gets both executed. In playground: class Vehi...
Norean asked 7/4, 2015 at 23:54

4

Solved

How can you set a property's value in Swift, without calling its didSet() function outside of an initialization context? The code below was a failed experiment to achieve this within the classes' n...
Pilarpilaster asked 19/8, 2014 at 22:48

3

I'm working on a swift project and I have a couple of arrays. In one of my arrays, I do not want the client to be able to mutate it without using one of my specially-defined methods. On the other h...
Fair asked 2/7, 2015 at 16:7

11

Solved

Swift has a property declaration syntax very similar to C#'s: var foo: Int { get { return getFoo() } set { setFoo(newValue) } } However, it also has willSet and didSet actions. These are calle...
Gospodin asked 3/6, 2014 at 2:32

2

Solved

I rarely see people using [weak self] in didSet. Is there a reason for this? I tried to use [weak self] in my didSet of a variable: var data: Dictionary<String, Any>! { // [1] didSet { [2]...
Benzocaine asked 29/4, 2017 at 8:58

4

Solved

I need the code in didSet to be executed without changing the property's value. Coming from Objective-C recently, there doesn't seem to be a setMyProperty(). So I tried: self.myProperty = self.m...
Vasily asked 5/10, 2016 at 7:6

1

Solved

It's well-known that, of course, didSet will not run on the same object again from inside a didSet. (example.) However. It seems that: the restriction applies not only to that object, but to maybe...
Cognate asked 9/2, 2017 at 18:56

1

Solved

I love this Swift syntax; it's very helpful for many things: var foo: Bar = Bar() { willSet { baz.prepareToDoTheThing() } didSet { baz.doTheThing() } } and I'd love to do this in Kotlin. How...
Iolaiolande asked 4/10, 2016 at 0:2

3

When overriding the didSet observer of a property results in recursion, why? class TwiceInt { var value:Int = 0 { didSet { value *= 2 } } } class QuadInt : TwiceInt { override var value:Int...
Blanks asked 21/1, 2015 at 12:57

2

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Swift (from the book 《iOS Animations by Tutorials:Chapter 12》 released by http://www.raywenderlich.com/): let photoLayer = CALayer() @IBInspectable var image: UIImage! { didSet { photoLayer.co...
Jephthah asked 24/9, 2015 at 8:5

1

Solved

I have a class as property with a property observer. If I change something in that class, is there a way to trigger didSet as shown in the example: class Foo { var items = [1,2,3,4,5] var number...
Forras asked 5/4, 2015 at 3:14

1

Solved

In my FirstViewController I have a button directing to my SecondViewController, passing data to a property in the SecondViewController. This property has a property observer, creating a new instanc...
Aurangzeb asked 31/3, 2015 at 7:39
1

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